US4156749A - Elastic multilayer packaging film containing plasticized polyvinyl chloride - Google Patents

Elastic multilayer packaging film containing plasticized polyvinyl chloride Download PDF

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Publication number
US4156749A
US4156749A US05/870,599 US87059978A US4156749A US 4156749 A US4156749 A US 4156749A US 87059978 A US87059978 A US 87059978A US 4156749 A US4156749 A US 4156749A
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Prior art keywords
film
outer layer
vinyl acetate
mil
phr
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US05/870,599
Inventor
Stanley Lustig
Stephen J. Vicik
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Viskase Corp
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Union Carbide Corp
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Priority to US05/870,599 priority Critical patent/US4156749A/en
Priority to CA318,964A priority patent/CA1115197A/en
Priority to EP19790300073 priority patent/EP0003404A1/en
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Publication of US4156749A publication Critical patent/US4156749A/en
Assigned to VISKASE CORPORATION, A CORP. OF PA. reassignment VISKASE CORPORATION, A CORP. OF PA. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: UNION CARBIDE CORPORATION, A CORP. OF NEW YORK
Assigned to CONTINENTAL BANK N.A. reassignment CONTINENTAL BANK N.A. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: VISKASE CORPORATION
Assigned to CITICORP NORTH AMERICA, INC. reassignment CITICORP NORTH AMERICA, INC. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SANDUSKY PLASTICS, INC., VISKASKE CORPORATION
Assigned to BT COMMERCIAL CORPORATION, AS COLLATERAL AGENT reassignment BT COMMERCIAL CORPORATION, AS COLLATERAL AGENT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: VISKASE CORPORATION
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Assigned to VISKASE CORPORATION reassignment VISKASE CORPORATION RELEASE OF SECURITY INTEREST Assignors: BT COMMERICIAL CORPORATION
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/22—Layered products comprising a layer of synthetic resin characterised by the use of special additives using plasticisers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/304—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/51—Elastic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
    • B32B2309/08—Dimensions, e.g. volume
    • B32B2309/10—Dimensions, e.g. volume linear, e.g. length, distance, width
    • B32B2309/105—Thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2439/00—Containers; Receptacles
    • B32B2439/70—Food packaging
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1334—Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
    • Y10T428/1341—Contains vapor or gas barrier, polymer derived from vinyl chloride or vinylidene chloride, or polymer containing a vinyl alcohol unit
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
    • Y10T428/2495—Thickness [relative or absolute]
    • Y10T428/24967—Absolute thicknesses specified
    • Y10T428/24975—No layer or component greater than 5 mils thick
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31855—Of addition polymer from unsaturated monomers
    • Y10T428/31909—Next to second addition polymer from unsaturated monomers
    • Y10T428/31913—Monoolefin polymer
    • Y10T428/3192—Next to vinyl or vinylidene chloride polymer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31855—Of addition polymer from unsaturated monomers
    • Y10T428/31909—Next to second addition polymer from unsaturated monomers
    • Y10T428/31928—Ester, halide or nitrile of addition polymer

Definitions

  • the present invention relates to an elastic multilayer film, and more particularly to a two-layer film suitable for use in the packaging of poultry.
  • one of the typical commercial packaging operations of frozen poultry includes the following steps:
  • a bag suitable for these steps must be formed from a film exhibiting good dimensional stability, production controllable thickness, non-tacky surfaces, and economical production.
  • the film must have good resistance to abrasion and impact because the shipping of the bagged turkey meat usually results in the abrasion of bags against each other as well as their mutual impacts.
  • One prior art film used to fabricate bags for the turkey meat is a plasticized vinyl film.
  • the bags formed from this film have the drawback that an unsatisfactory percentage of bags became damaged during the shipping step.
  • an elastic multilayer film suitable for use in connection with the packaging of poultry comprising a first outer layer including a plasticized polyvinyl chloride having an inherent viscosity greater than about 1.10 and having a plasticizer content of from about 35 phr to about 40 phr, and a second outer layer including an ethylene vinyl acetate copolymer having a vinyl acetate content of from about 16% to about 20% by weight and having a melt flow of from about 1.0 to about 3.0 decigrams per minute.
  • the first outer layer has a thickness of from about 1.75 mils to about 2.0 mils and the second outer layer has a thickness of from about 0.5 mil to about 0.75 mil.
  • the film consists of the two outer layers.
  • a thickness of 0.75 mil for the second outer layer and vinyl acetate content of about 18% by weight are preferable.
  • the plasticizer is at least 27 phr of a food approved plasticizer such as dibutyl sebacate or a di-n-hexyl azelate which are low temperature plasticizers.
  • the remaining plasticizer is preferably an epoxidized soybean oil.
  • An ethylene vinyl acetate copolymer having a vinyl acetate content greater than about 20% by weight generally results in a film having insufficient strength.
  • An ethylene vinyl acetate copolymer having a melt flow less than about 1.0 decigram per minute is undesirable because of the difficulty in processing this type of resin at die temperatures preferably for plasticized polyvinyl chloride extrusion. A melt flow too high tends to weaken the puncture resistance of the film.
  • the processes of forming the film of the invention and bags can be carried out using conventional blown film extrusion processes.
  • a two-layer film is coextruded into tubular form, air cooled to a temperature below the softening point, and then wound into rolls for subsequent fabrication into bags.
  • the temperatures of the elbow and die of the extrusion device are critical for obtaining satisfactory films according to the invention and these temperatures must be adjusted so that the temperature of the inside of the extruded tube of film and the temperature between the two layers is relatively cool. These temperatures are readily identifiable to persons in the art because the film leaving the extrusion device has a visual appearance of having a low gloss level.
  • the preferred conditions correspond to a temperature of about 425° F. at the exit of the die.
  • Two layer films were produced with a first outside layer of a plasticized polyvinyl chloride including 27.5 phr of dibutyl sebacate and 10.0 phr of epoxidized soybean oil, and a second outer layer of an ethylene vinyl acetate copolymer as shown in Table 3.
  • a plasticized polyvinyl chloride including 27.5 phr of dibutyl sebacate and 10.0 phr of epoxidized soybean oil
  • a second outer layer of an ethylene vinyl acetate copolymer as shown in Table 3.
  • the extrusion equipment includes a 21/2 inch 16:1 L/D NRM oil heated extruder to feed the plasticized polyvinyl chloride.
  • the barrel temperature was maintained at about 300° F. and the screw speed was about 22 rpm.
  • the ethylene vinyl acetate extruder was a 11/4 inch-18:1 L/D TEC extruder with the barrel temperature maintained at about 320° F. and a screw speed of about 34 rpm.
  • a 60 mm diameter two layer die was used with the plasticized vinyl chloride as the inner layer and the ethylene vinyl acetate copolymer as the outer layer.
  • the die base temperatures were maintained at about 425° F. while the exit temperature varied from about 425° F. to about 475° F.
  • Conventional blown film methods were used to cool and flatten the bubble. The film speed was about 50 fpm.
  • the TITE-WRAP test is a test especially relevant to the intended use of the film of the invention.
  • the tubular film is cut to a length of about one foot long and podwered to reduce its coefficient of friction and placed on two sets of jaws which are connected to pneumatic cylinders. The jaws are rapidly opened so that the circumference of the film is increased by about 50%.
  • the EVA's A and B showed satisfactory performance in the properties tested. Surprisingly, a film having a second outer layer about 0.5 mil in thickness was stronger than a film having a second outer layer about 1.0 mil in thickness.
  • Examples 10 to 17 were carried out with an endeavor to produce a film using conventional methods in order to compare the performance of additional polymers for the second outer layer.
  • the first outer layer was the same as the example 1.
  • Table 4 shows the results of the examples 10 to 17. None of these examples produced a film satisfactory for commercially packaging poultry.
  • the example 18 is a known single layer plasticized vinyl used for packaging poultry.
  • the examples 19 to 21 are films of the inventions with the dimensions shown and comprising the materials of the example 1. Also shown in the Table 5 are the extrusion conditions for the films and the breakage during packaging and shipping of bags fabricated from the films.
  • the Table 5 shows the superior performance of the film according to the invention and the importance of the extrusion temperature on bag performance.
  • Example 22 is a conventional single layer film of plasticized vinyl and examples 23 to 40 are films with the materials of the example 1 prepared under various conditions and different layer thicknesses as shown in Table 6.
  • temperatures of the inside of the tubular film and between the layers can be estimated by a person having ordinary skill in the art by visual appearance (gloss) on the film. Temperatures at the exit of the die which are broadly referred to as “cold”, “warm”, and “hot” correspond respectively to about 425° F., about 450° F., and about 475° F.
  • the single layer film of the example 22 was included to provide a comparison to the prior art.
  • the Dynamic Tensile test includes cycling a sample to a 50 inches per minute jaw speed from 0 to 200% elongation at about -40° F. and recording the average number of cycles to failure.
  • the film condition was visually determined based on the gloss of the film.
  • the plasticized polyvinyl chloride in the examples 23 to 38 was the same as in the previous examples.
  • the plasticizer was 30 phr dibutyl sebacate.
  • the examples 24 to 28 show that reducing the temperature of the extrusion system provides an improved tensile strength.
  • the examples 29 to 35 generally were run at relatively cool extrusion temperatures and provide a comparison between films having layers of different thicknesses. While the impact strength of each of the examples 32 and 33 was high, the dynamic tensile strength for each was low.
  • the thickness of the first outer layer was varied along with the amount of plasticizer.

Landscapes

  • Laminated Bodies (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)

Abstract

{PG,1 An elastic multilayer film suitable for use in connection with the packaging of poultry, comprises a first outer layer including a plasticized polyvinyl chloride having an inherent viscosity greater than about 1.10 and having a plasticizer content of from about 35 phr to about 40 phr, and a second outer layer including an ethylene vinyl acetate copolymer having a vinyl acetate content of from about 16% to about 20% by weight and having a melt flow of from about 1.0 to about 3.0 decigrams per minute.

Description

The present invention relates to an elastic multilayer film, and more particularly to a two-layer film suitable for use in the packaging of poultry.
Generally, one of the typical commercial packaging operations of frozen poultry includes the following steps:
1. Enclosing boneless turkey meat in a string netting;
2. Enclosing the netted turkey meat in an elastic bag by mechanically expanding the bag to approximately 140% of its normal circumference, placing the netted turkey meat in the bag, and thereafter, allowing the bag to relax to its normal size to form a tight package;
3. Generally evacuating the air from the bag and clipping the end of the bag closed;
4. Quick freezing the bagged turkey meat to a temperature as low as about -40° C.; and
5. Shipping the frozen turkey meat in the bag.
A bag suitable for these steps must be formed from a film exhibiting good dimensional stability, production controllable thickness, non-tacky surfaces, and economical production. In addition, the film must have good resistance to abrasion and impact because the shipping of the bagged turkey meat usually results in the abrasion of bags against each other as well as their mutual impacts.
One prior art film used to fabricate bags for the turkey meat is a plasticized vinyl film. The bags formed from this film have the drawback that an unsatisfactory percentage of bags became damaged during the shipping step.
In accordance with the present invention, there is provided an elastic multilayer film suitable for use in connection with the packaging of poultry, comprising a first outer layer including a plasticized polyvinyl chloride having an inherent viscosity greater than about 1.10 and having a plasticizer content of from about 35 phr to about 40 phr, and a second outer layer including an ethylene vinyl acetate copolymer having a vinyl acetate content of from about 16% to about 20% by weight and having a melt flow of from about 1.0 to about 3.0 decigrams per minute. Preferably, the first outer layer has a thickness of from about 1.75 mils to about 2.0 mils and the second outer layer has a thickness of from about 0.5 mil to about 0.75 mil.
Preferably, the film consists of the two outer layers. In addition, a thickness of 0.75 mil for the second outer layer and vinyl acetate content of about 18% by weight are preferable.
Preferably, the plasticizer is at least 27 phr of a food approved plasticizer such as dibutyl sebacate or a di-n-hexyl azelate which are low temperature plasticizers. The remaining plasticizer is preferably an epoxidized soybean oil.
An ethylene vinyl acetate copolymer having a vinyl acetate content greater than about 20% by weight generally results in a film having insufficient strength. For a vinyl acetate content less than about 16% by weight, there is poor adhesion between the two outer layers.
An ethylene vinyl acetate copolymer having a melt flow less than about 1.0 decigram per minute is undesirable because of the difficulty in processing this type of resin at die temperatures preferably for plasticized polyvinyl chloride extrusion. A melt flow too high tends to weaken the puncture resistance of the film.
Generally, the processes of forming the film of the invention and bags can be carried out using conventional blown film extrusion processes.
Preferably, a two-layer film is coextruded into tubular form, air cooled to a temperature below the softening point, and then wound into rolls for subsequent fabrication into bags. It has been discovered that the temperatures of the elbow and die of the extrusion device are critical for obtaining satisfactory films according to the invention and these temperatures must be adjusted so that the temperature of the inside of the extruded tube of film and the temperature between the two layers is relatively cool. These temperatures are readily identifiable to persons in the art because the film leaving the extrusion device has a visual appearance of having a low gloss level. The preferred conditions correspond to a temperature of about 425° F. at the exit of the die.
Illustrative, non-limiting examples of the practice of the invention are set out below. Numerous other examples can readily be evolved in the light of the guiding principles and teachings contained herein. The examples given herein are intended mainly to illustrate the invention and not in any sense to limit the manner in which the invention can be practiced.
All percentages and parts stated herein are by weight unless otherwise stated.
As used herein, the term "phr" has the conventional meaning of parts per 100 parts of polymer.
The materials described herein have their properties determined in accordance with the following test methods:
Melt Flow--ASTM D-1238 -57T at 44 psi and 190° C.
Viscosity--ASTM D-1243
In the examples, the materials shown in Tables 1 and 2 were employed:
              TABLE 1                                                     
______________________________________                                    
                                Commercial                                
Ethylene  Melt Flow Vinyl Acetate                                         
                                Identification                            
Vinyl Acetate                                                             
          dg/min.   Weight Percent                                        
                                And Source                                
______________________________________                                    
EVA A     2.5       18          DQDE-1868                                 
                                Union Carbide                             
                                Corp.                                     
EVA B     2.5       18          EVA 3170 E.I.                             
                                du Pont de                                
                                Nemoirs                                   
EVA C     9.0       18          EVA 3172 E.I.                             
                                du Pont de                                
                                Nemoirs                                   
EVA D     20        18          EVA 4227 E.I.                             
                                du Pont de                                
                                Nemoirs                                   
EVA E     0.7       18          EVA 3165 E.I.                             
                                du Pont de                                
                                Nemoirs                                   
EVA F     0.8        91/2       EVA 4210 E.I.                             
                                du Pont de                                
                                Nemoirs                                   
______________________________________                                    

              TABLE 2                                                     
______________________________________                                    
                                Commercial                                
          Melt Flow             Identification                            
Polymer   dg/min.   Description and Source                                
______________________________________                                    
EEA A     5-7       ethylene-ethyl                                        
                                DPD-6169 Union                            
                    acrylate; 18%                                         
                                Carbide Corp.                             
                    ethyl acrylate                                        
EEA B     0.1       ethylene-ethyl                                        
                    acrylate; 2%                                          
                    ethyl acrylate                                        
Polyethylene C                                                            
          0.7       polyethylene;                                         
                                DGDJ-6095                                 
                    density     Union Carbide                             
                    0.961 g/cm.sup.3                                      
                                Corporation                               
Polybutylene D                                                            
          2.0       polybutylene;                                         
                                Witron 1200                               
                    density     Witco Chemical                            
                    0.91 g/cm.sup.3                                       
                                Corp.                                     
Polyurethane E      polyurethane;                                         
                                Estane 5701                               
                    density     B.F. Goodrich                             
                    1.20 g/cm.sup.3                                       
                                Chemical Co.                              
Ionomer F           12% ethylene-                                         
                                Surlyn 1650                               
                    methacrylic E. I. Du Pont                             
                    acid copolymer;                                       
                                de Nemoirs                                
                    37% conversion                                        
                    to a zinc salt                                        
EDMA      1.5       ethylene                                              
                    dimethylacryl-                                        
                    amide, 14%                                            
                    amide                                                 
______________________________________
EXAMPLES 1 to 9
Two layer films were produced with a first outside layer of a plasticized polyvinyl chloride including 27.5 phr of dibutyl sebacate and 10.0 phr of epoxidized soybean oil, and a second outer layer of an ethylene vinyl acetate copolymer as shown in Table 3.
Generally, the extrusion equipment includes a 21/2 inch 16:1 L/D NRM oil heated extruder to feed the plasticized polyvinyl chloride. The barrel temperature was maintained at about 300° F. and the screw speed was about 22 rpm. The ethylene vinyl acetate extruder was a 11/4 inch-18:1 L/D TEC extruder with the barrel temperature maintained at about 320° F. and a screw speed of about 34 rpm. A 60 mm diameter two layer die was used with the plasticized vinyl chloride as the inner layer and the ethylene vinyl acetate copolymer as the outer layer. The die base temperatures were maintained at about 425° F. while the exit temperature varied from about 425° F. to about 475° F. Conventional blown film methods were used to cool and flatten the bubble. The film speed was about 50 fpm.
                                  Table 3                                 
__________________________________________________________________________
                                        % of                              
                                        Breakage                          
                                  Impact                                  
                                        for                               
                    Tensile       Strength at                             
                                        TITE-WRAP                         
     Layer Thickness                                                      
              First Strength                                              
                           Elongation                                     
                                  0° F./40° F./             
                                        at 50%                            
     First/Second                                                         
              Layer MD/TD  MD/TD  Rm. Temp.                               
                                        Stretch Extrusion                 
                                                        Layer             
Example                                                                   
     mil/mil  Polymer                                                     
                    psi/psi                                               
                           %/%    in-lbs./mil                             
                                        40° F.                     
                                                Performance               
                                                        Adhesion          
__________________________________________________________________________
1    1.5/0.5  EVA A 3300/2700                                             
                           280/290                                        
                                  33/38/33                                
                                        0       good    satisfactory      
2    1.0/1.0  EVA A 2500/2100                                             
                           245/250                                        
                                  15/28/26                                
                                        0       good    satisfactory      
3    1.5/0.5  EVA B 3300/2900                                             
                           260/300                                        
                                  31/38/40                                
                                        0       good    satisfactory      
4    1.0/1.0  EVA B 2500/2100                                             
                           250/270                                        
                                  22/27/33                                
                                        0       satisfactory              
                                                        satisfactory      
5    1.5/0.5  EVA C 3600/2900                                             
                           280/305                                        
                                  38/38/40                                
                                        0       good    satisfactory      
6    1.0/1.0  EVA C 2500/2300                                             
                           275/270                                        
                                  14/29/34                                
                                        40      unsatisfactory            
                                                        satisfactory      
7    1.5/0.5  EVA D 3600/2900                                             
                           290/310                                        
                                  35/36/42                                
                                        0       good    satisfactory      
8    1.0/1.0  EVA D 2500/2000                                             
                           270/250                                        
                                  11/25/26                                
                                        40      unsatisfactory            
                                                        satisfactory      
9    1.0/1.0  EVA E 2600/2400                                             
                           280/290                                        
                                  27/33/29                                
                                        0       unsatisfactory            
                                                        satisfactory      
__________________________________________________________________________
For the examples 1 to 9, the EVA's A, B, C, D, and E were used as well as different layer thicknesses. Observations on the extrusion performance and layer adhesion are indicated in addition to various physical properties of the films. The TITE-WRAP test is a test especially relevant to the intended use of the film of the invention. The tubular film is cut to a length of about one foot long and podwered to reduce its coefficient of friction and placed on two sets of jaws which are connected to pneumatic cylinders. The jaws are rapidly opened so that the circumference of the film is increased by about 50%.
Although EVA's C and D showed acceptable results for the respective examples 5 and 7, the unsatisfactory results of the related examples 6 and 8 indicate that the layer thicknesses suitable for commercial use might be unreliable. The EVA E presented problems in the extrusion because of the high viscosity, as indicated by the relatively low melt flow, is unsatisfactory at the temperatures suitable for vinyl extrusion.
The EVA's A and B showed satisfactory performance in the properties tested. Surprisingly, a film having a second outer layer about 0.5 mil in thickness was stronger than a film having a second outer layer about 1.0 mil in thickness.
EXAMPLES 10 to 17
Examples 10 to 17 were carried out with an endeavor to produce a film using conventional methods in order to compare the performance of additional polymers for the second outer layer. The first outer layer was the same as the example 1.
Table 4 shows the results of the examples 10 to 17. None of these examples produced a film satisfactory for commercially packaging poultry.
EXAMPLES 18 to 21
Examples 18 to 21 were carried out to demonstrate the necessity of maintaining the extrusion conditions relatively cool.
The example 18 is a known single layer plasticized vinyl used for packaging poultry. The examples 19 to 21 are films of the inventions with the dimensions shown and comprising the materials of the example 1. Also shown in the Table 5 are the extrusion conditions for the films and the breakage during packaging and shipping of bags fabricated from the films.
                                  Table 4                                 
__________________________________________________________________________
                                       Impact                             
                                       Strength at                        
      Layer Thickness Tensile Strength                                    
                                Elongation                                
                                       0° F./at 50° F./     
      First/Second                                                        
               First Layer                                                
                      MD/TD     MD/TD   Rm. Temp.                         
                                               Extrusion                  
                                                       Layer              
Example                                                                   
      mil/mil  Polymer                                                    
                      psi/psi   %/%    in-lbs./mil                        
                                               Performance                
                                                       Adhesion           
__________________________________________________________________________
10    1.5/0.5  EEA A  3200/2700 300/330                                   
                                       17/39/43                           
                                               weld line                  
                                                       unsatisfactory     
                                               in film                    
11    1.0/1.0  EVA F  2700/2400 310/320                                   
                                       17/28/34                           
                                               good    unsatisfactory     
12    1.0/1.0  EEA B  2800/2100 300/300                                   
                                       12/29/32                           
                                               good    unsatisfactory     
13    1.0/1.0  Poly-  material too tacky                                  
               butylene D                                                 
14    1.0/1.0  EDMA   2700/2300 290/300                                   
                                       16/30/31                           
                                               heavy weld                 
                                                       satisfactory       
                                               line in film               
15    1.0/1.0  Poly-  2600/2400 315/300                                   
                                       1.5/14/31                          
                                               poor edges                 
                                                       unsatisfactory     
               ethylene C                      and holes                  
16    1.0/1.0  Poly-  material too tacky                                  
               urethane E                                                 
17    1.0/1.0  Ionomer F                                                  
                      material too tacky                                  
__________________________________________________________________________

              Table 5                                                     
______________________________________                                    
       Film Layer               Total                                     
       Thicknesses              % Breakage                                
       First/Second   Extrusion During Packaging                          
Example                                                                   
       mil/mil        Conditions                                          
                                and Shipping                              
______________________________________                                    
18     Single Layer 1.75 mils                                             
                      normal    33.5                                      
19     1.5/0.5        hot       61.2                                      
20     1.75/0.75      cold      11.0                                      
21     2.0/0.75       cold       5.5                                      
______________________________________
The Table 5 shows the superior performance of the film according to the invention and the importance of the extrusion temperature on bag performance.
EXAMPLES 22 to 40
Example 22 is a conventional single layer film of plasticized vinyl and examples 23 to 40 are films with the materials of the example 1 prepared under various conditions and different layer thicknesses as shown in Table 6.
Generally, the temperatures of the inside of the tubular film and between the layers can be estimated by a person having ordinary skill in the art by visual appearance (gloss) on the film. Temperatures at the exit of the die which are broadly referred to as "cold", "warm", and "hot" correspond respectively to about 425° F., about 450° F., and about 475° F.
The single layer film of the example 22 was included to provide a comparison to the prior art.
The Dynamic Tensile test includes cycling a sample to a 50 inches per minute jaw speed from 0 to 200% elongation at about -40° F. and recording the average number of cycles to failure.
The film condition was visually determined based on the gloss of the film.
                                  TABLE 6                                 
__________________________________________________________________________
              Layer Thicknesses                                           
                        Film Condition                                    
                                Dynamic Tensile                           
                                          Impact                          
     Special  First/Second                                                
                        Inside/Between                                    
                                at -40° F.                         
                                          Strength                        
Example                                                                   
     Conditions                                                           
              mil/mil   Tube/Layers                                       
                                Cycles to Failure                         
                                          in-lbs/mil                      
__________________________________________________________________________
22   Single layer                                                         
              1.75      Cold    4-6       14.6                            
23   Normal   1.5/0.5   Hot/Cold                                          
                                2.5-4     26.4                            
24   Hot elbow                                                            
              1.75/0.5  Warm/Warm                                         
                                7.0       12.1                            
25   Normal   1.75/0.5  Hot/Warm                                          
                                6.6       14.2                            
26   Normal   1.75/0.5  Warm/Cold                                         
                                9.3       8.6                             
27   Cold elbow                                                           
              1.75/0.5  Warm/Cold                                         
                                no failure after 10                       
                                          14.8                            
28   Normal   1.75/0.5  Hot/Cold                                          
                                6.0       11.9                            
29   Normal   1.5/0.5   Warm/Cold                                         
                                8.0       30.9                            
30   Cold elbow                                                           
              1.75/0.5  Warm/Cold                                         
                                7.6       21.3                            
31   Normal   2.0/0.5   Warm/Cold                                         
                                7.6       28.5                            
32   Normal   2.0/0.75  Warm/Cold                                         
                                2.6       30.9                            
33   Normal   1.75/0.75 Warm/Cold                                         
                                1.0       26.1                            
34   Aux. die heater                                                      
              1.75/0.75 Warm/Cold                                         
                                2.0       11.0                            
35   Aux. die heater                                                      
              1.75/0.75 Hot/Warm                                          
                                4.0       13.6                            
     plus hot pipe                                                        
36   Normal   1.5/0.75  Cold/Cold                                         
                                7.0       8.3                             
37   Normal   1.75/0.75 Cold/Cold                                         
                                no failure after 10                       
                                          18.8                            
38   Normal   2.0/0.75  Cold/Cold                                         
                                no failure after 10                       
                                          39.8                            
39   Normal   2.0/0.75  Cold/Cold                                         
                                7.6       59.9                            
40   Normal   1.75/0.75 Cold/Cold                                         
                                no failure after 10                       
                                          48.2                            
__________________________________________________________________________
The plasticized polyvinyl chloride in the examples 23 to 38 was the same as in the previous examples. In the examples 39 and 40, the plasticizer was 30 phr dibutyl sebacate.
The examples 24 to 28 show that reducing the temperature of the extrusion system provides an improved tensile strength.
The examples 29 to 35 generally were run at relatively cool extrusion temperatures and provide a comparison between films having layers of different thicknesses. While the impact strength of each of the examples 32 and 33 was high, the dynamic tensile strength for each was low.
For the examples 36 to 40, the thickness of the first outer layer was varied along with the amount of plasticizer. These examples provided the best results for both the dynamic tensile and the impact strength tests.
We wish it understood that we do not desire to be limited to the exact details shown and described, for obvious modifications will occur to a person skilled in the art.

Claims (12)

Having described the invention, what we claim as new and desire to be secured by Letters Patent is as follows:
1. An elastic multilayer film adapted for packaging of poultry, consisting essentially of a first outer layer including a plasticized polyvinyl chloride having an inherent viscosity greater than about 1.10 and having a plasticizer content of from about 35 phr to about 40 phr; and a second outer layer including an ethylene vinyl acetate copolymer having a vinyl acetate content of from about 16% to about 20% by weight and having a melt flow of from about 1.0 to about 3.0 decigrams per minute.
2. The film of claim 1, wherein the vinyl acetate is about 18% by weight.
3. The film of claim 1, wherein said layers are in physical contact with each other.
4. The film of claim 1, wherein said second outer layer has a thickness of about 0.75 mil.
5. The film of claim 4, wherein the vinyl acetate is about 18% by weight.
6. The film of claim 1, wherein said plasticizer includes dibutyl sebacate.
7. The film of claim 1, wherein said dibutyl sebacate is at least about 27 phr.
8. The film of claim 7, wherein said plasticizer further includes epoxidized soybean oil.
9. The film of claim 1, wherein said plasticizer includes di-n-hexyl azelate.
10. The film of claim 1, wherein said melt flow is about 1.0 decigram per minute.
11. The film of claim 1, wherein said first outer layer has a thickness of from about 1.75 mils to about 2.0 units and said second outer layer has a thickness of from about 0.5 mil to about 0.75 mil.
12. A bag fabricated from the film of claim 1.
US05/870,599 1978-01-18 1978-01-18 Elastic multilayer packaging film containing plasticized polyvinyl chloride Expired - Lifetime US4156749A (en)

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US05/870,599 US4156749A (en) 1978-01-18 1978-01-18 Elastic multilayer packaging film containing plasticized polyvinyl chloride
CA318,964A CA1115197A (en) 1978-01-18 1979-01-02 Multilayer packaging film plasticized with pvc
EP19790300073 EP0003404A1 (en) 1978-01-18 1979-01-17 Multi-layer plastics film suitable for use as a packaging bag

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4320174A (en) * 1980-09-15 1982-03-16 The B. F. Goodrich Company Transparent and translucent vinyl polymeric composite
US5019432A (en) * 1986-12-05 1991-05-28 Ube Industries, Ltd. Container for stabilized aqueous phosphoenolpyruvic acid
WO2000003875A3 (en) * 1998-07-17 2000-04-20 Cryovac Inc Multilayer film with polyolefin and polyvinyl chloride
WO2004041536A1 (en) * 2002-11-05 2004-05-21 Vismore Company S.A. Stretchable thermoplastic resin film, for use in the packaging of food
US20110226410A1 (en) * 2008-05-08 2011-09-22 Empting Jr Harry V Edge Banding
US20150064414A1 (en) * 2008-05-08 2015-03-05 Harry V. EMPTING, JR. Primerless Edge Banding

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3741253A (en) * 1971-03-30 1973-06-26 Grace W R & Co Laminates of ethylene vinyl acetate polymers and polymers of vinylidene chloride
US3932693A (en) * 1970-10-19 1976-01-13 Continental Can Company, Inc. Laminated packaging film having low vapor and gas permeability
US3953660A (en) * 1974-03-29 1976-04-27 Tamapoly Co., Ltd. Surface protective film for plasticized polyvinyl chloride substrates
US4057667A (en) * 1972-03-24 1977-11-08 American Can Company Oriented saran coextrudate

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1171123A (en) * 1966-05-11 1969-11-19 Grace W R & Co Improvements relating to Shrink Packaging.
US3607505A (en) * 1967-08-11 1971-09-21 Grace W R & Co Method of producing a laminated tubular article
CA1028110A (en) * 1972-12-27 1978-03-21 Sumitomo Bakelite Company Adhesive comprising post-chlorinated polyethylene and polyvinyl chloride

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932693A (en) * 1970-10-19 1976-01-13 Continental Can Company, Inc. Laminated packaging film having low vapor and gas permeability
US3741253A (en) * 1971-03-30 1973-06-26 Grace W R & Co Laminates of ethylene vinyl acetate polymers and polymers of vinylidene chloride
US4057667A (en) * 1972-03-24 1977-11-08 American Can Company Oriented saran coextrudate
US3953660A (en) * 1974-03-29 1976-04-27 Tamapoly Co., Ltd. Surface protective film for plasticized polyvinyl chloride substrates

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4320174A (en) * 1980-09-15 1982-03-16 The B. F. Goodrich Company Transparent and translucent vinyl polymeric composite
US5019432A (en) * 1986-12-05 1991-05-28 Ube Industries, Ltd. Container for stabilized aqueous phosphoenolpyruvic acid
WO2000003875A3 (en) * 1998-07-17 2000-04-20 Cryovac Inc Multilayer film with polyolefin and polyvinyl chloride
US6214477B1 (en) 1998-07-17 2001-04-10 Cryovac, Inc. Multilayer film with polyolefin and polyvinyl chloride
WO2004041536A1 (en) * 2002-11-05 2004-05-21 Vismore Company S.A. Stretchable thermoplastic resin film, for use in the packaging of food
US20060099392A1 (en) * 2002-11-05 2006-05-11 Vismore Company S.A. Stretchable thermoplastic resin film, for use in the packaging of food
US20110226410A1 (en) * 2008-05-08 2011-09-22 Empting Jr Harry V Edge Banding
US20150064414A1 (en) * 2008-05-08 2015-03-05 Harry V. EMPTING, JR. Primerless Edge Banding

Also Published As

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EP0003404A1 (en) 1979-08-08

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